Electronic devices employ various technologies for power-saving. For example, when an electronic device does not output a screen through a display or does not change a currently output screen during a specified period of time, the processor of the electronic device may be changed into a sleep operation. When the processor is in the sleep operation, an amount of power consumed for driving the processor is reduced when compared to the case of a processing operation and thus, power is saved.
When the electronic device needs to output a new screen, or needs to change a currently output screen, the processor that is in the sleep operation may wake up and perform a processing operation. In the processing operation, the processor may execute an operation and a screen update, to output the new screen or to change the currently output screen.